Liquid pressure control valves of this nature are well known for the control of water pressure, the flexible member typically being a diaphragm. A drawback with these valves is the possibility that excess closing pressure may cause the flexible member to collapse or distort and thus destroy its closing capability. Extreme cases have resulted in the flexible member fracturing necessitating replacement. To overcome or at least limit these problems it is known to provide a rigid backing element, typically a metal plate, associated with the flexible member to prevent or at least effectively limit excessive displacement or distortion thereof. Such an arrangement is disclosed in our patent NZ Patent # 328862. A drawback with providing such a plate is that it can tend to impede the liquid flow through the valve.
An object of this invention is to provide a liquid pressure control valve that includes a flexible member as aforesaid and which also includes a displacement and distortion limiting element therefor that has minimal if any impediment on the flow through the valve. A further object is to provide the public with a useful choice.